1. Scope of the Invention
This invention relates to the process of hydroformylating olefins with syngas in the presence of a novel catalyst composition to form aldehydes. More particularly, it relates to an improved olefin hydroformylation catalyst system comprising a mixture of platinum (II) and acetylacetonate; a Group IVB metal halide; and a bidentate tertiary ligand, each of which components is described in further detail below.
The novel organo metallic complex catalyst composition of this invention provides high reaction rates and high ratios of linear to branched aldehydes.
2. Description of the Prior Art
Processes of preparing aldehydes by hydroformylating an olefin with syngas, i.e., a mixture of hydrogen and carbon monoxide, in the presence of various catalysts, particularly cobalt and rhodium catalysts, is well known in the art. See, for example, Kirk-Othmer Encyclopedia of Chemical Technology ("OXO process"). Depending upon the catalyst, varying rates of reaction, and more importantly, different ratios of linear to branched aldehydes are obtained, the linear aldehydes being the preferred ones (as intermediates in the conversion, e.g., to alcohols by known hydrogenation methods and the like).
The use of platinum (II) complexes as hydroformylation catalysts in the OXO process, either alone, or in combination with SnCl.sub.2, is known. Higher ratios of straight to branched aldehydes are obtained when tertiary phosphine-coordinated platinum complexes are used.
For example, PtH(SnCl.sub.3)(PPh.sub.3).sub.2 is shown by Hsu and Orchin, J. Amer. Chem Soc., 97, 353 (1975) to be useful for conversion of 1-pentene to aldehydes. Schwager and Knifton, J. Cat., 45, 256 (1976), U.S. Pat. No. 3,981,925 and U.S. Pat. No. 3,996,293 disclose use of PtCl.sub.2 (PPh.sub.3).sub.2 +SnCl.sub.2 for a similar reaction with 1-heptene. Kawabata, et al., J.C.S. Chem. Comm, 462 (1979) teach Pt(PhCN).sub.2 Cl.sub.2 +Ph.sub.2 P(CH.sub.2).sub.x PPh.sub.2 for conversion of 1-pentene to aldehydes. U.S. Pat. Nos. 4,101,565 and 4,155,939 show the dimer (PtCl.sub.2 PPh.sub.3).sub.2 +SnCl.sub.2 for hydroformylation of 1-hexene. U.S. Pat. No. 3,876,672 also shows hydroformylation of 1-hexene with PtH(PPh.sub.3).sub.3.sup.+ HSO.sub.4.sup.-. See also, U.S. Pat. No. 4,405,496, which describes a platinum (acetylacetonate) in combination with a Group IVB metal halide and a tertiary phosphine. Also, U.S. Pat. No. 4,370,258 teaches the combination of platinum (II) complexed with phosphorus-,arsenic-, or antimony-containing bidentate ligands in combination with Group IVB metal halides, as hydroformylation catalysts. Other effective platinum (II) compounds include the ionic complexes shown in U.S. Pat. No. 3,876,672.
Generally speaking, however, it is recognized that platinum complex-based hydroformylation catalysts usually give slower reaction rates compared to those of the early cobalt and rhodium catalysts. It is, therefore, an object of this invention to provide an olefin hydroformylation catalyst which both gives faster reaction rates, and also maintains a high selectivity for linear over branched aldehydes.